Hi,
I'm very new to RMAN, I've some issue with my rman setup, Could you help fix it? Details are below

Env detail : 10.2.0.4 Oracle DBs, running in Sun Solaris 5.9

I recently refreshed my dev DB with Release DB by regular OS coping of datafiles.
After that I changed the dev DB's dbid using nid. Both the datasebases uses Rman catalog for backup/recovery. I registeded the dev db with rman after refresh as the dbid got changed. but after this refresh activity release database backup is not happening. it throws the below error

RMAN-06004: ORACLE error from recovery catalog database:
RMAN-20004: target database name does not match name in recovery catalog

There is no need to register the DEV database (the one that was restored) again to catalog, unless you want to backup it or do other rman operations.
For issues like this, I always use separate catalog users(separate schema inside catalog database) for each database to be registered.
In your case, you have one catalog for two databases.
DEV is registered and rman catalog is currently looking into it.
Register REL database again and give a try.